from gurobipy import *
import pandas as pd
import numpy as np

Nodes = [1, 2, 3, 4, 5, 6, 7]

Arcs = {(1, 2): 15,
        (1, 4): 25,
        (1, 3): 45,
        (2, 5): 30,
        (2, 4): 2,
        (5, 7): 2,
        (4, 7): 50,
        (4, 3): 2,
        (3, 6): 25,
        (6, 7): 1}
org = 1
des = 7

model = Model('SSP model')
X = {}
for key in Arcs.keys():
    index = 'x_' + str(key[0]) + ',' + str(key[1])
    X[key] = model.addVar(vtype=GRB.BINARY, name=index)
print(X)
obj = LinExpr(0)

for key in Arcs.keys():
        obj.addTerms()
